Ataxia due to abnormalities in the cerebellum may be inherited, acquired, or arise from yet unknown reasons.
- Inherited/genetic: autosomal dominant; autosomal recessive; X-linked; associated with a mitochondrial disorder
- Acquired: structural/demyelinating; toxic/metabolic; paraneoplastic; infectious/postinfectious; autoimmune
- Idiopathic (cause not known): cerebellar form of multiple system atrophy (known as MSA); Idiopathic cerebellar degeneration
A diagnostic approach to ataxia may include:
- Neurological and medical history, including drug and toxin exposures
- Family history of neurological problems
- Neurological and medical examinations
- Blood tests to rule out specific deficiencies and toxins
- Urine screen for mercury exposure
- Brain imaging: magnetic resonance imaging (MRI) or computed tomography (CT)
- Neuroimaging of the spinal cord.
- Electrophysiologic testing (electromyography and nerve conduction velocity testing) if there are signs or symptoms of peripheral nerve dysfunction
Searching for a specific diagnosis in patients with ataxia of unknown cause is highly recommended. Investigation may reveal a reversible cause of cerebellar dysfunction, such as vitamin E deficiency, Wilson’s disease, cerebellar dysfunction due to thyroid abnormalities, or cerebellar injury due to a toxin.
If no acquired cause of ataxia is found, or if the history suggests an inherited cerebellar disease, specific genetic testing is indicated. Examples include blood testing for Friedreich’s ataxia or any of the testable spinocerebellar ataxias (SCAs). Genetic disorders may arise anew, so that genetic testing is indicated if all others results are unrevealing.
A specific diagnosis is useful to provide prognostic information for the patient and family. A concrete diagnosis usually leads to reduction in anxiety. Most patients tell us that they feel better knowing the name of their ataxia, even if a specific treatment has not yet been discovered. If test results are negative, a patient with ataxia may have the cerebellar form of multiple system atrophy (MSA), idiopathic cerebellar degeneration, or a new type of ataxia for which no specific test is yet available.
If there is no evidence that the ataxia is inherited and the progression of symptoms is rapid, it is important to search for a tumor that may be responsible for indirect (paraneoplastic) cerebellar degeneration. Investigations for tumors in patients with unexplained ataxia usually include CTs of the chest, abdomen, and pelvis in addition to blood testing for paraneoplastic antibodies. If a tumor is found, therapy is directed at the primary tumor. Successful treatment of such a tumor may improve or retard progression of paraneoplastic cerebellar degeneration, although this is not always the case.
Signs and symptoms of ataxia may be worsened by:
- Alcohol use
- Anxiety or stress
- Medications that affect the brain, such as excessive doses of medicine prescribed for insomnia, anxiety or mood disorders.
Patients with a neurological disorder tend to be more sensitive to side effects of neuroactive medications and are advised to start new medications at low doses and to increase the dose slowly.